Portable electronic imaging devices such as digital cameras or digital video cameras often include a zoom feature. This feature may be provided optically, through the use of a zoom lens, or by cropping (and possibly rescaling) the digital image. The latter method is often referred to as “digital zoom.”
Though simple and inexpensive to implement, digital zoom has a major disadvantage: loss of resolution upon rescaling to a larger image size. A digital image may be scaled to a larger image size by using the existing pixel information to estimate the added pixels. The simplest method replicates the value of the nearest neighbor pixel. More sophisticated techniques use interpolation to generate an intermediate pixel value from several neighboring pixels. Bilinear and bicubic interpolation are examples of these techniques. Every rescaling method, particularly pixel replication, produces an image that suffers in quality at high zoom factors, even if the portable electronic imaging device has reasonably high resolution. Providing the portable electronic imaging device with even higher resolution to compensate for digital zoom adds to the cost of the device. Although an optical zoom lens avoids the major disadvantage of digital zoom, an optical zoom lens may add bulk, weight, and cost to the portable electronic imaging device.
It is thus apparent that there is a need in the art for an improved-resolution digital zoom capability in a portable electronic imaging device.